The present invention relates to an ink jet recording head for expanding or contracting a part of a pressure generating chamber communicating with a nozzle aperture by an actuator for flexural oscillation so as to jet an ink droplet from the nozzle aperture.
An ink jet recording head has two types of a piezoelectric vibration type for mechanically deforming a pressure generating chamber and pressurizing ink and a bubble jet type provided with a heater element in a pressure generating chamber for pressurizing ink by the pressure of bubbles generated because of the heat of the heater element. The piezoelectric vibration type of recording head is further classified into two types of a first recording bead using a piezoelectric vibrator displaced in an axial direction and a second recording head using a piezoelectric vibrator displaced by flexure. As for the first recording head, although high-speed driving is enabled and recording in high density, there is a problem that the number of manufacturing steps in large because cutting is required for machining a piezoelectric vibrator and three-dimensional assembly is required when a piezoelectric vibrator is fixed to a pressure generating chamber.
In the meantime, as for the second recording head, as a silicon monocrystalline substrate is used for base material, a pressure generating chamber and a passage such as a reservoir are formed by anisotropic etching, an elastic film can be extremely thin and the pressure generating chamber and a piezoelectric vibrator can be formed very precisely by forming the piezoelectric vibrator using a film forming technique such as sputtering piezoelectric material. Also, the opening area of the pressure generating chamber can be reduced as much as possible and recording density can be enhanced.
However, as a metallic plate is still used for a nozzle plate to maintain the working precision of a nozzle aperture, there is a problem that the whole recording head is distorted due to differential thermal expansion when the piezoelectric vibrator is fixed by burning. Such a problem can be solved by using a thermal expansion characteristic adjusting member disclosed in Japanese Patent Application Unexamined Publication No. Hei. 6-122197. However, there is a problem that if a piezoelectric vibrator is constituted by sputtering piezoelectric material, the piezoelectric vibrator is thin and a higher electric field is applied in the case of driving at the same voltage, compared with a piezoelectric vibrator constituted by burning a green sheet. Therefore, if humidity in the atmosphere is absorbed, leak current between driving electrodes is readily increased and finally, dielectric breakdown is caused.